"We look forward to welcoming a new team member who will be a key player in not only fostering positive change within the organization, but also in upholding the tradition of excellence US Speedskating was founded on," said Mike Plant, president of US Speedskating, in a news release. "We thank Mark for his leadership and commitment over the past three years, and look forward to his continued involvement with the sport."

Greenwald has yet to respond to NPR's request for comment. He said in the news release, "It is my goal to ensure the sport's legacy of tremendous athletic achievement continues."

Speedskaters have won more Olympic medals for the United States than any other Winter Olympic sport.

Alarmed by the turmoil so close to the 2014 Olympics, the U.S. Olympic Committee installed Plant as the new board president. Plant is an Olympic veteran and Atlanta Braves vice president. He has already shrunk the size of the USS board and is working on making the sports governing body financially stable.

USS spokeswoman Tamara Castellano says Greenwald had planned to step down after February's Sochi Olympics but decided to resign now "to hand over the reins given all of the changes" as the group reorganizes.

"The timing of it seemed to make sense," Castellano adds.

"We believe that this will clear the way for further reforms," says Ed Williams, an attorney who represents more than a dozen short track skaters who filed complaints against USS, its coaches and Greenwald.

The most alarming allegation involved short track Olympic medalist Simon Cho and former short track coach Jae Su Chun. Cho admitted to sabotaging the skate of Canadian Olivier Jean at an international meet in Poland in 2011 but claimed Chun ordered him to do it.

The hearing was closed to the media but NPR has obtained Jean's sworn written statement. Jean testified that Chun complained that the Canadian team was using "dirty skating" tactics during the competition.

Just before the tampering incident, according to Jean, Chun told him, "If Canada wants to use dirty tactics, as a Korean, I know worse dirty tactics to make someone lose."

The American and Canadian teams shared a locker room at the event and Cho used a blade device to bend Jean's skate blade slightly. In the relay that followed, Jean's skate wouldn't track properly and he was forced out of the race.

Chun's attorney, Russell Fericks, did not immediately respond to NPR's request for comment. We'll post his response here if he responds.

The ISU says it expects to issue a decision soon on sanctions for Chun and Cho. Both could be barred from the sport for life.

USS says Greenwald will remain on the job until a replacement is found and a transition is completed. Castellano says the group's goal is to have a new executive director in place before the Olympic season begins in earnest in the fall.